Our invention relates to an apparatus for data transfer with disklike record media, and more specifically to an apparatus for the recording and/or reproduction of coded data with use of interchangeable flexible magnetic disks, now commonly referred to as floppy disks, that are housed in protective envelopes or jackets to make up disk cartridges. Still more specifically, out invention deals with improvement in such a data transfer apparatus of the class having a pair of magnetic heads for data transducing contact with the opposite faces of the magnetic disk.
Flexible magnetic disks may be described as being either single or double sided depending upon whether one or both of its opposite faces are used for data storage. A data transfer apparatus for use with double sided disks or disk cartridges has a pair of magnetic transducer heads. The first of these heads is substantially fixed in a direction normal to the plane of the magnetic disk. The second transducer head is typically mounted on a pivotal head arm for movement therewith into and out of data transfer contact with the magnetic disk. A solenoid has been a familiar example of actuator for such pivotal motion of the head arm. An advantage of this prior art construction is that the head arm can be readily solenoid actuated to move the second transducer head away the magnetic disk for the travel of both heads in its radial direction for track to track accessing, thereby avoiding damage or wear of the disk due to friction that would otherwise be caused by sliding engagement of the disk with both transducer heads. Offsetting this advantage, however, are the longer access time and the higher cost of the apparatus because of the use of the solenoid.
These weaknesses are absent from the data transfer apparatus described and claimed in Japanese Laid Open Patent Application No. 58-77080 filed by the assignee of the instant application and laid open to public inspection on May 10, 1983. This prior art device teaches to interlock the second transducer head with the disk clamp mechanism and hence to dispense with the solenoid. The second transducer head is sprung into data transfer contact with the magnetic disk as the clamp mechanism is hand actuated to clamp the disk against the drive hub assembly following the loading of the disk cartridge into the apparatus.
This solution has proved not truly satisfactory, however. The user may inadvertently actuate the clamp mechanism when no disk cartridge is loaded in the apparatus. Then the second transducer head, mounted on the pivotal head arm, will be spring energized into direct contact with the first head. Since the opposed faces of both transducer heads have a smooth, mirrorlike finish to offer a minimum friction to the magnetic disk, they will stick together upon direct contact with each other, so firmly that they may not easily come apart. Such direct contact of the transducer heads under spring pressure may also result in the destruction of their gimbal supports.
An obvious remedy for this problem is to lock against operation the clamp actuating means such as a hand lever when no disk cartridge is loaded. The clamp actuating means may be unlocked in response to the insertion of a disk cartridge in the entrance slot. The use of mechanical, rather than electrical, means is preferable in thus unlocking the clamp actuating means for the simpler construction and lower cost of the apparatus. However, should the locking means be left in contact with the disk cartridge after having been tripped thereby, such means would exert a pressure on the magnetic disk via its envelope. The thus increased frictional resistance against the rotation of the magnetic disk would might result in a decrease in the speed of disk rotation. The magnetic disk might also partly deflect under pressure from the locking means, giving rise to fluctuations in the pressure of contact between the disk and the transducer heads. All in all, the proper data transfer between disk and heads might become impossible.